Add elevation transition class elv-transition

src/_maketheme.scss

@@ -24,6 +24,10 @@ $button-color: #CCCCCC !default;
     }
 }
 
+.elv-transition {
+    @include ElevationTransition();
+}
+
 
 @function darken-brighten-color($color, $val) {
     @if (lightness($color) > 50) {

src/dark.scss

@@ -9,4 +9,8 @@ $disabled-brightness: 1.1;
     z-index: $dp;
 }
 
+@mixin ElevationTransition() {
+    transition: background .5s;
+}
+
 @import "./_maketheme.scss";

src/light.scss

@@ -54,4 +54,8 @@ $disabled-brightness: .9;
     z-index: $dp;
 }
 
+@mixin ElevationTransition() {
+    transition: box-shadow .5s;
+}
+
 @import "./_maketheme.scss";